lockwood



(No Model.)

' R. M. LOGKWOOD.

RECEIVER FOR TELEPHONES.

No. 256,906. Patented Apr. 25, 1882.

W1 TWESSES NITED STATES PATENT OFFICE.

ROBERT M. LOOKWOOD, OE NEW YORK, N. Y., ASSIGNOR TO THE MOLECU- LAR TELEPHONE COMPANY, OF SAME PLACE.

RECEIVER FOR TELEPHONES.

SPECIFICATION forming part of Letters Patent No. 256,906, dated April 25, 1882.

(N model.)

To all whom it may concern:

Be it known that I, ROBERT M. LooKWoon, of New York, county of New York, State of New York, have invented new and useful Improvements in Receivers for Telephones, of

which the following is a full, clear, and exact description, reference being bad to the accompanying drawings, making part of this specifieation, in which Figure 1 is a side view of my improved receiver, partly in section, showing the construction and arrangement of the diaphragm, 850.; and Fig. 2 is a plan or face view of the central disk of the diaphragm detached.

My invention relates to a novel construction of the diaphragm of a telephonereceiver; and it consists in making said diaphragm of cork or equivalent non-resonant and non-magnetic material, provided with a central perforation covered by a glass plate or disk; also, in the combination, with such perforated disk, of disks or plates of glass arranged upon its opposite sides, covering the perforation and forming a sound-chamber in the disk between them;

and, lastly, in a specific construction of diaphragm, consisting of a central perforated disk,

a ring surrounding said disk, and a plate or plates of glass covering the perforation therein, as hereinafter explained.

In the accompanying drawings, A represents the cylindrical handle of the receiver, B the metal cup forming the sound-chamber, O the coil or helix D the magnet with its yielding or reduced extension d in the form of a re- 3 5 curved arm or spring, E the diaphragm, and

G the ear-piece, said parts, except in particulars hereinafter described, being constructed and arranged in a manner described in a11- other application of even date herewith.

The disk or diaphragm is made of cork or some equivalent non-resonant and non-magnetic material-such as compressed cotton or other fiber-and is composed of two partsviz., a central perforated disk or flat ring, E, 5 and an inclosing-ring, E-said parts being held in place in the receiver by means of clamping-rin gs F F, described in another application above referred to. The perforation in the central disk is covered by a disk or plate, 71, of thin glass, and one of these may be applied on each side of the diaphragm, as shown at h h, in such manner as to form a sound chamber in the diaphragm between them. These plates may be let into the cork so as to be flush on their outer faces therewith, or they may be secured directly to the surfaces thereof in any convenient manner; and they may, if desired, have their outer surfaces ground or roughened, so as to give a rasping action upon the end of the recurved arm d of the magnet resting on the face of the one adjacent thereto. By this construction the yielding extension or recurved arm of the magnet, instead of resting upon the soft yielding surface of the cork, ismade ,to rest upon a hard vitreous surface or button applied thereto in such manner as to combine the glass with its peculiar resonant properties with a material non-resonant and non-magnetic in its character, and which acts molecularly in transmitting to the ear disturbances in the current or in degree of polarity in the magnet recorded on the glass.

By giving to the glass resting in contact with the flexible arm of the magnet a ground or rasping surface, as explained, any movement or vibration of said arm across said surface under the disturbances in its degree of polarity will be rendered more apparent to the ear, and these again will be magnified through the medium of the drum or sound-chamber form ed in the diaphragm, where the two plates or disks of glass or equivalent material are applied on opposite sides of the diaphragm. This construction also makes the diaphragm much more durable than where cork only is used.

Having now described my invention, I claim- 1. In a telephone-receiver, adiaphragm composed of cork or equivalent non-resonant and non-magnetic material and provided with a. central perforation, in combination with a disk or plate of glass covering said perforation, substantially as described.

2. The diaphragm of cork, provided with a central perforation, in combination with disks or plates of glass arranged on opposite sides of said diaphragm, covering the perforation In testimony whereof I have hereunto set therein and forming a sound-chamber between my hand this 9th day of September, A. D. 1881. I0 them.

3. The diaphragm ofcork, made in two parts, ROBT. M. LOOKWOOD. 5 consisting of a central perforated disk and a ring surrounding said disk, in combination Witnesses: with a plate or plates of glass covering the GEO. BELL,

perforation in said central disk. CHRIS. SCHULTZ. 

